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Asparagus Can Play Important Role In Crop Diversification

LAS CRUCES--Asparagus, a high-value perennial crop that can remain productive for 15 years, may prove valuable to New Mexican farmers wanting to diversify.

Harvested in the spring, asparagus can be an income source when there's normally a cash flow problem associated with planting costs for other crops, said a horticulture specialist with New Mexico State University.

"Diverse agricultural operations that include asparagus can distribute farm labor throughout the growing season," said George Dickerson, horticulture specialist with NMSU's Cooperative Extension Service. "It's often hard to find labor near the end of the summer for harvesting other crops. Planting and harvesting asparagus and other spring crops will help stabilize your work force throughout the growing season."

Asparagus is propagated from one-year-old crowns spaced 12 inches apart in furrows 6 to 8 inches deep. Rows should be 5 feet apart. Crowns are placed in the bottom of the furrows with the buds facing up, covered with 2 to 3 inches of soil and then irrigated.

"Asparagus spears should not be harvested the first year," Dickerson said. "Instead, allow spears to develop ferns. As the ferns grow, gradually add more soil back on the crowns until a bed is formed with irrigation furrows on either side." Sidedress the beds with nitrogen fertilizer to promote vigorous growth.

Allowing the ferns to grow the first season will promote a strong root system. Ferns can be cut back to ground level during the winter. Harvest spears lightly the second year and plan a full harvest the third growing season.

"The harvest period for asparagus varies from four to eight weeks," Dickerson said. "Snap spears off at ground level while the growing tip is still tight." When the average diameter of the spears is less then one-quarter inch, stop harvesting and allow ferns to form. "This will replenish carbohydrates in the root system for next year's crop," he said.

Older varieties of asparagus like 'Mary Washington' produce both male and female plants. Female plants generate seed, which makes them less productive. Male plants out-produce female plants, because all energy is devoted to spear production.

"All-male hybrid varieties like 'Jersey Giant' or 'Jersey Knight' can yield 4,000 to 10,000 pounds per acre depending on location," Dickerson said. "Heavier yields occur in warmer regions." Many of these varieties also have greater tolerance or resistance to diseases like Fusarium wilt and rust.